1. Field of the Invention
The present invention relates to motor driven cameras in which a single motor serves as the only electro-mechanical transducer in an exposure adjusting device and also performs another non-contemporaneous camera function, such as a film advancing and shutter cocking function or a shutter releasing function.
2. Description of the Prior Art
Conventional automatic exposure control devices used in cameras include at least one electro-mechanical transducer for regulating the shutter and/or diaphragm element in response to an electrical signal related to scene luminance. For example such a transducer may comprise a so-called stepper motor, a galvanometer, a solenoid, or an electro-magnet.
In addition to one or more transducers employed in an exposure control system, many cameras include additional electro-mechanical transducers, such as electric motors, to perform sequentially other non-contemporaneous camera functions e.g. to simultaneously advance the film and cock the shutter, to focus the objective lens, and to release the cocked shutter.
In some cases in which the same electric motor is used to advance the film and cock the shutter, it also performs another subsequent function that often is performed manually in analogous types of cameras. For example, U.S. Pat. No. 3,098,418 issued to W. Reiher on July 23, 1963 shows a camera in which an electric motor drives the film advancing and shutter cocking mechanism. Upon completion of that operation, the motor is disengaged automatically from the mechanism and is coupled to a lens focusing mechanism, which is then adjustable by means of a manually operated switch that both energizes and controls the direction of rotation of the motor. In another construction, the motor used simultaneously to wind film and cock the shutter has also been employed subsequently in cooperation with other transducers used for different purposes. For example, U.S. Pat. No. 2,983,207, issued to K. Gebele on May 9, 1961 shows such a camera, in which a single motor advances the film and simultaneously cocks the shutter, adjusts the shutter speed or aperture or both by moving corresponding members to positions determined by the needle of a galvanometer, and then initiates the release of the camera shutter by de-energizing an electromagnet.
It has also been proposed previously to use the same motor employed for film advancing and shutter cocking in a different transducer mode of operation to perform a second function. For example, in the camera shown in U.S. Pat. No. 3,613,542 issued to W. Wiessner on July 8, 1968, when the operator presses the shutter release button, a switch is closed to energize a motor that first runs in a predetermined direction to trip the shutter and then automatically reverses its direction of rotation to simultaneously advance the film and re-cock the shutter. In U.S. Pat. No. 3,928,859, issued to D. M. Peterson on Mar. 22, 1974, a motor is coupled to the film winding and shutter cocking mechanism through a one-way clutch and to the focusing mechanism through a slip clutch. When a button is depressed to initiate an exposure, the motor runs in a predetermined direction, with the one-way clutch preventing operation of the film advancing and shutter cocking mechanism while the slip clutch drives the lens from its far-focus position toward its near-focus position. An automatic focusing system de-energizes the motor when the lens has reached its proper position, whereupon a solenoid releases the cocked shutter. Upon completion of exposure, the motor runs in the opposite direction and the one-way clutch drives the mechanism that cocks the shutter and advances the film in preparation for the next exposure. While these two functions are being performed, the slip clutch returns the lens to its far position and then slips to allow the shutter cocking and film advancement operation to proceed to completion.
For purposes of convenience and clarity, some of the foregoing references have been described as if each operating cycle begins with the release of the shutter release, but it should be understood that in all cases a film advancing and/or shutter cocking function preceeds subsequent functions performed by the motor to expose the film area thus brought into exposure position. Accordingly, the important consideration is not the manner in which a sequence of functions is described, but, rather, the fact that each of the foregoing references discloses the use of a single motor to perform two mutually non-contemporaneous functions, thereby providing an opportunity to eliminate one or more separate electro-mechanical transducers. However, none of these references shows or suggests a construction in which a single motor performs a focusing or exposure control function and at least two other non-contemporaneous functions, such as a film winding and/or shutter cocking function, and a shutter releasing function. Furthermore, the reference constructions inherently obviate such applications. For example, the termination of rotation of the motor establishes the exposure control adjustment and the lens focus adjustment in the respective Gebella and Petersen references, but, because the motor remains coupled to the adjusted element, the motor cannot subsequently be employed to trip the shutter without destroying the adjustment that it previously affected. Similarly, if a mechanism of the type disclosed by the Weissner references is used to trip the shutter by reversing the motor after completion of the shutter cocking and/or film advancing function, reversed motor rotation cannot also perform a lens focusing or exposure control adjustment at the necessary time, i.e. immediately prior to release of the shutter. Furthermore, all of the reference constructions inherently preclude using the same motor that advances the film and/or cocks the shutter to perform a focusing or exposure adjusting function involving selective bi-directional motor rotation.